Winds will be strongest overnight and early on Friday, gusting between 110 and 130 km/h (80mph) at coasts.
Weather warnings have been put in place from 6am on Friday across western parts of the United Kingdom, as torrential rains and heavy winds are set to strike the country.
A Status Orange weather warning will come into effect for 13 counties tonight.
It is due to pass to the west of Ireland, northern England and Scotland during Friday.
Winds of up to 60 miles per hour are expected to hit the area, which combined with high tides could lead to some coastal impact due to large waves.
In Galway, Mayo, Donegal, Sligo, and Clare, the orange warning will remain in place until 5pm on Friday.
The Met Office said both Friday and Saturday are expected to be wet and windy days as Storm Callum moves in from the Atlantic. There is a chance of gusts of 70 to 80 miles per hour in the Western Isles during Friday afternoon and evening.
After the worst of the wind has swept the country, the tail-end of Hurricane Leslie will bring rainfall, raising the prospect of coastal and river flooding.
Ireland's national forecaster Met Eireann has also warned of severe flooding along coasts. Expect the unexpected. Watch out for falling/fallen debris on the road and vehicles veering across the road.
Train services between Swansea and Carmarthen are being suspended during parts of Friday because of Storm Callum. This is also set to elapse at 9am on Friday morning.
The county council is urging motorists to avoid all coastal roads, and to only make essential journeys.
Coats on the south and west of the country are expected to be the worst affected by the storm, worth risks of heavy flooding and structural damage. Rain will clear to showers in Northern parts but further heavy rain is likely to spread into Southern and Eastern areas with the ongoing flooding risk.